JP2004020792A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain toner concentration stabilization control overcoming the drawbacks of a recording device by the prior art by improving a toner concentration control means of a developing machine in particular, in an image forming method for repetitively forming a multiplicity of sheets of images with a high-speed recording device of an electrophotographic method and an electrostatic recording method etc. <P>SOLUTION: The developing device supplies toners to an electrostatic latent image on an image carrier of the electrostatic recording device which develops the electrostatic latent image formed on an image carrier by using the toners, transfers the toner image onto a recording medium and obtains a recorded image by fixing the toner image transferred onto the recording medium onto the recording medium by a fixing step. The developing device detects the number of driving times of a toner replenishing member for replenishing the toners to a developing section from a toner hopper section and the value for regulating the toner concentration stabilization control is controlled from the number of driving times. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus that repeatedly forms a large number of images in an electrophotographic method, an electrostatic recording method, and the like, and relates to a toner hopper section that stores replenishment toner in a developing machine that supplies toner to an image carrier, and a developing section that uses the toner. The present invention relates to an image forming apparatus using a toner replenishing member for replenishing toner.
[0002]
[Prior art]
A conventional printing method will be described. In an electrophotographic recording apparatus, a photoconductive photoreceptor is uniformly charged, then exposed, and a partial charge discharge occurs on the photoreceptor to form an electrostatic latent image. Thereafter, the electrostatic latent image is developed with a toner containing a colorant. As a developing device that supplies toner to the electrostatic latent image formed on the photoreceptor, in addition to a one-component developing device using only toner as a developer, a developer containing a toner and a carrier is used. A developing device of the two-component developing system described above is known. The toner image thus obtained is transferred and fixed on a recording medium such as a recording paper to obtain a recorded image. Such a process is repeatedly performed for a long time.
[0003]
Next, a two-component developing method using a developer containing a toner and a carrier will be described. When toner is supplied to the photoreceptor for development, the toner concentration in the developer gradually decreases.To maintain the toner concentration in the developer, when the toner concentration decreases to some extent, the toner supply member is driven. And replenish new toner. The toner supply method of the two-component developing method has been described above.
[0004]
Next, conventional toner density control will be described. A toner concentration in a developer containing a toner and a carrier is measured by a toner concentration detector provided in the developing machine. When this output value is lower than the set value, it is determined that the toner density has decreased, and the toner replenishing member is driven until the value of the toner density detector reaches the set value to replenish new toner. I have. This set value is set for each number of printed pages, and is controlled so that the toner density is always constant.
[0005]
[Problems to be solved by the invention]
In the conventional toner concentration control and toner replenishment method of the two-component developing method described above, the toner concentration is controlled for each number of printed pages. However, there is a problem that the same control is performed because the print quality does not change, and the print quality is adversely affected. In addition, the output value of the toner density detector is easily affected by the charging characteristics of the developer, which results in an erroneous detection of the output value. As a result, toner is excessively replenished to the developing section, and the toner density becomes higher. There is a problem that the stain on the image background increases.
[0006]
Therefore, an object of the present invention is to provide a stable toner density control means even when a problem occurs between the set number of printed pages or when a toner density detector erroneously detects due to the charging characteristics of the developer. To provide.
[0007]
[Means for Solving the Problems]
According to the present invention, an electrostatic latent image formed on an image carrier is visualized using toner, the toner image is transferred onto a recording medium, and the toner image transferred onto the recording medium is fixed by a fixing step. In a developing device for supplying toner to an electrostatic latent image on an image carrier of an electrostatic recording apparatus for fixing a recording image on a recording medium to obtain a recorded image, a toner replenishing member for replenishing toner from a toner hopper section to the developing section When the number of times of driving exceeds the upper limit value and the lower limit value of the specified range continuously, the fact is displayed on the message board when the number of times exceeds the second time.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram schematically showing a cross section of the electrostatic recording device according to the present invention. The process of the present apparatus will be described with reference to FIG. The photoconductor 1 having photoconductivity is uniformly charged by the charger 2, and forms a latent image by the laser beam of the optical device 3. After that, the developing device 4 installed in the vicinity of and close to the photoreceptor 1 performs development using the toner 5 and the developer 6 including the toner and the carrier. The toner 5 that has been developed and adhered to the surface of the photoconductor 1 is transferred onto a sheet 7 by a transfer unit 8 that applies a polarity opposite to the charging polarity of the toner 5. The toner 5 transferred onto the paper 7 is provided by a fixing device 9 including a heat roll 10 for applying heat to the toner 5 and a pressure roll 11 for applying pressure to the toner 5 on the paper 7 and the heat roll 10 provided on the back of the paper 7. The toner 5 is fixed on the sheet 7 to form a final image. On the other hand, the toner 5 remaining on the photoconductor 1 without being transferred is removed from the photoconductor 1 by the cleaning device 12. This process is repeated.
[0009]
FIG. 2 is an enlarged view of the developing device 4 and the toner concentration stabilizing control means according to the present invention. The developing device 4 has a toner hopper 13 for storing the toner 5 to be supplied to the developing section at an upper portion, and a toner replenishing member 14 for supplying the toner 5 at a lower portion thereof. A transport roll 15 for transporting the developer 6 including the toner and the carrier to the developing roll 16 is provided below the developing roll 16, and the developing roll 16 comes into contact with the photoreceptor 1 to perform development. A toner density detector 17 for detecting the ratio of the toner in the developer 6 is provided below the developing roll 16.
[0010]
Next, the toner concentration stabilization control means according to the present invention will be described. As in the conventional case, the toner concentration detector 17 including a magnetic permeability sensor and a magnetic bridge sensor detects the proportion of the toner in the developer 6. If the toner concentration control device 21 is lower than the set value, the toner 5 is consumed by printing. Then, it is determined that the toner concentration in the developer 6 has decreased, and the driving device 18 of the toner supply member 14 drives the toner supply member 14 to supply toner to the developing unit. At this time, the drive signal of the toner replenishing member 14 is detected by the detecting device 19 and is detected as the number of times of driving. The number of times the toner replenishing member 14 is driven is detected at a fixed number of printed pages or at intervals of time. A specified range of the number of times of driving of the toner replenishing member 14 is input to the toner density control device 21 from the conventional data, and this specified range is compared with the number of times of driving of the toner replenishing member 14 detected by the detection device 19. I do. As a result, when the number of times of driving of the toner supply member 14 exceeds the upper limit of the specified range, the following phenomenon is considered. The charging characteristic of the developer 6 is degraded, and the toner density detector 17 is erroneously detected. In fact, although the toner density is high, the detected value is detected as the toner density is low. Over-supply, which exceeds the upper limit of the specified range. Thereby, the toner density also increases. In order to prevent these, if the number of times of driving of the toner replenishing member 14 detected by the detecting device 19 exceeds the upper limit value of the specified range, the above phenomenon is expected. The toner density control device 21 controls to lower by one rank. As a result, replenishment of toner to the developing section is suppressed, and an increase in toner density is prevented.
[0011]
Next, another embodiment of the present invention will be described with reference to FIG. A description will be given of the toner concentration stabilization control means when the fluidity of the toner is deteriorated. There is no abnormality in the charging characteristics of the developer, and the value of the toner concentration detector 17 is accurately detected. However, if the fluidity of the toner is poor, the replenishing amount per drive of the toner replenishing member 14 is reduced, and the toner is replenished. The number of times that the supply member 14 is driven increases, and exceeds the upper limit of the above-mentioned specified range. In this state, if the toner density control device 21 controls to lower the toner density stabilization control adjustment value, the number of times of driving of the toner replenishing member 14 decreases, the replenishment amount of the toner 5 to the developing unit decreases, and the developer 6 The density of the toner inside is reduced, and the image density on the paper is reduced. In order to prevent this, when the number of times of driving of the toner replenishing member 14 detected at a certain number of printed pages or every time exceeds the upper limit value of the specified range, the adjustment value of the toner density control device 21 is changed for the first time. Continue printing without doing so. Further, if the number of driving of the toner replenishing member 14 continues to exceed the upper limit of the specified range, after printing is completed, the message board 20 indicates that the number of driving of the toner replenishing member 14 exceeds the upper limit of the specified range. Is displayed to prompt the user to confirm the image quality. When the image quality is not affected, it is determined that the number of times of driving of the toner replenishing member 14 is increased because the fluidity of the toner is poor, and the printing is continued with the normal control. When the image quality is degraded, the toner density in the developer 6 is always kept constant even if the fluidity of the toner is degraded by controlling the adjustment value of the toner density control device 21 so as to decrease. Quality can be kept stable.
[0012]
If the fluidity of the toner is too good, the replenishment amount per driving of the toner replenishing member 14 is increased, and the number of times of driving the toner replenishing member 14 is reduced, and falls below the lower limit of the specified range. In this case as well, the message is displayed on the message board at the second time point when the number of consecutive times exceeds, prompting the user to confirm the image quality.
[0013]
When the number of times of driving of the toner replenishing member 14 exceeds the upper limit and the lower limit of the specified range for three consecutive times, and the number of times of driving of the toner replenishing member 14 is maintained at a constant number of times, the characteristics of the developer 6 Is not displayed on the message board.
[0014]
Another embodiment of the present invention will be described with reference to FIGS. As the printing rate per page increases, the toner consumption per page increases accordingly. Accordingly, the amount of toner 5 supplied to the developing unit is increased to maintain the toner density, and the number of times the toner supply member 14 is driven also increases. Therefore, the number of times the toner supply member 14 is driven increases as the printing rate per page increases. For this reason, it exceeds the upper limit of the specified range. As a result, when the toner density control device 21 controls the adjustment value of the toner density stabilization control to lower by one rank, the balance between toner consumption and toner replenishment in the developing unit is lost, and the toner density in the developer decreases, and the image density decreases. And other problems occur. The toner density stabilization control means for preventing these phenomena will be described.
[0015]
When the number of drive times of the toner replenishing member 14 is one, the print rate always exceeds the upper limit of the specified range due to an increase in the printing rate. Therefore, based on the conventional data, the printing rate and the range of the number of times of driving of the toner replenishing member 14 per fixed number of printed pages are set as shown in FIG. 3, and this data is stored in the toner density control device 21. The user selects the specified range corresponding to the printing rate used in accordance with the change of the printing rate, so that the number of driving of the toner replenishing member 14 according to the increase of the printing rate per page can be increased. The number of times the toner replenishing member 14 is driven falls within a specified range, and the toner density can be constantly controlled.
[0016]
【The invention's effect】
According to the present invention described above, the number of times of driving of the toner replenishing member for replenishing toner to the developing unit is detected. By controlling the adjustment value of the toner density control device based on the value, in the conventional toner density control for each number of printed pages, even if a problem related to the toner density occurs due to any problem between the set number of printed pages. Thus, it is possible to provide stable toner density control that addresses this problem.
[0017]
In addition, when the number of times of driving the toner supply member continuously exceeds the upper limit value and the lower limit value of the set range, the content is displayed on a message board to urge the user to confirm the image quality and to improve the image quality. If the image quality has not deteriorated, the control is continued, and if the image quality has deteriorated, the adjustment value of the toner density control device is readjusted, so that the toner density control can be stably performed even if the characteristics of the toner, the developer, etc. change. Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating a cross section of an entire electrophotographic electrostatic recording apparatus according to the present invention.
FIG. 2 is a diagram relating to a developing device and toner concentration stabilization control according to the present invention.
FIG. 3 is a diagram illustrating a relationship between a printing rate and a prescribed number of drive times of a toner supply member per a fixed number of printed pages.
[Explanation of symbols]
1 is a photoreceptor, 2 is a charger, 3 is an optical device, 4 is a developing machine, 5 is a toner, 6 is a developer, 7 is a paper, 8 is a transfer device, 9 is a fixing device, 10 is a heat roll, 11 is A pressure roll, 12 a cleaning device, 13 a toner hopper, 14 a toner supply member, 15 a transport roll, 16 a developing roll, 17 a toner concentration detector, 18 a drive device, 19 a detection device, 20 a message board, Reference numeral 21 denotes a toner density control device.

Claims (4)

The electrostatic latent image formed on the image carrier is visualized using toner, the toner image is transferred onto a recording medium, and the toner image transferred onto the recording medium is fixed on the recording medium by a fixing process. In a developing device for supplying toner to an electrostatic latent image on the image carrier of an electrostatic recording device for fixing and obtaining a recorded image, the number of driving of a toner replenishing member for replenishing toner from a toner hopper portion to a developing portion is reduced. An image forming apparatus which detects and controls a toner density stabilization control adjustment value from the number of times of driving. The electrostatic latent image formed on the image carrier is visualized using toner, the toner image is transferred onto a recording medium, and the toner image transferred onto the recording medium is fixed on the recording medium by a fixing process. In a developing device that supplies toner to an electrostatic latent image on the image carrier of an electrostatic recording device that obtains a recorded image by fixing, the number of times of driving of a toner replenishing member for replenishing toner from a toner hopper to a developing unit is reduced. An image forming apparatus characterized in that, when the upper limit value and the lower limit value of the prescribed range are continuously exceeded, the fact is displayed on a message board at the time of exceeding the second time. 3. The image forming apparatus according to claim 2, wherein a toner density stabilization control adjustment value is controlled based on display contents of the message board. 2. The control device according to claim 1, wherein the control unit detects the number of times of driving of the toner supply member, compares the number of drive times with a specified range, and controls the toner density. 4. The image forming apparatus according to 2, 3 or 4.

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